Envelope openers of the prior art may be generally grouped as being power-operated or manually-operated, the latter group including those which are small enough to be held in one hand. For example the U.S. patent to Kettlestrings, issued Aug. 10, 1971 and bearing U.S. Pat. No. 3,597,843 discloses a pair of disks in a housing and having overlapping edge portions disposed in an envelope guide-slot. This device involves many elements, but more importantly the cutting means would tend to become loose after repeated use and thus cease to cut easily. Another U.S. patent to Fishman, issued Jan. 16, 1973, and having U.S. Pat. No. 3,710,444, discloses an apparatus with the same general shortcoming.